Polarized Light Microscopy Digital Image Gallery

Olivine Basalt Porphyry

Porphyritic basalts are relatively common and are found around the world. The phenocrysts contained in them vary somewhat, but are typically comprised of the silicate minerals pyroxene and olivine. Olivine is one of the most prolific substances found in the upper mantle of the Earth and has been found in meteorites as well. Typically green in color, perhaps the most familiar of these anisotropic minerals is peridot, a type of olivine that serves as the birthstone of August.